Multi-operational percussive tools



1966 J. F. ALcocK ETAL 3,231,028

MULTI'OPERATIONAL PERCUSSIVE TOOLS Filed Jan. 1'7, 1963 5 Sheets-Sheet l Jan. 25, 1966 J. F. ALcocK ETAL 3,231,028

MULTI-OPERATIONAL PERCUSSIVE TOOLS Filed Jan. 17, 1963 3 Sheets-Sheet 2 1965 J. F. ALCOCK ETAL MULTI-OPERATIONAL PERCUSSIVE TOOLS 3 Sheets-Sheet 5 Filed Jan. 1'7, 1963 United States 3,231,028 MULTl-UPERATIONAL PERCUSSIVE TOOLS John Forster Alcock and .Iames Albert Hoare, Shoreharnlay-Sea, and Eric el'vor Snowden, Harley, England, assignors to Warsep Power Tools Limited, Salforris,

Redhill, England, a British company Filed Jan. 17, 1963, Ser. No. 252,242 13 Claims. (Cl. l7376) The present invention is concerned with tools which can be used either as rock drills or as road breakers.

A rock drill has as essential elements a hammer piston which reciprocates so as to strike a tool bit which can slide but not rotate in a chuck. The chuck is rotated slightly at each stroke of the hammer piston, means for orientation of the operative end of the tool bit changes at each stroke. There is commonly provision for blowing air down an axial hole in the tool bit to clear the chippings.

In the case of a road breaker a difierent tool bit is used, but the important distinction from a rock drill is that there is no need to rotate the tool bit and no need to blow air through the tool bit. It is in fact desirable to lock the chuck so that the tool bit cannot rotate.

A tool according to the present invention includes a chuck to receive a tool bit, a hammer piston to strike the tool, a rotary drive mechanism for rotating the chuck slightly at each stroke of the hammer piston, means for supplying compressed air to a chamber at the inner end of the chuck, and an actuating member which is movable between a first position in which it causes or allows a detent to lock the chuck against rotation, and permits the compressed air in the chamber to escape to the atmosphere through a vent, and a second position in which it permits the chuck to be rotated by the rotary drive and substantially shuts off the air escape through the vent.

The actuating member is preferably arranged to disengage the rotary drive when it is in its first position. in the case of a tool including an internal combustion engine which drives the hammer piston, this is most easily achieved by means of a rotary drive mechanism which comprises a cam which is rotated by the internal combustion engine and which is arranged to act on a follower so as to oscillate about its own axis a shaft which drives the chuck by means of a unidirectional driving connection, the shaft being rotated by the actuating member so as to carry the follower clear of the cam when the actuating member is moved to its first position.

The two positions of the actuating member are preferably different angular positions about an axis of rotation, the actuating member being formed with a cam surface which controls the detent. There is preferably also a second cam surface which, when the actuating member is in its first position, holds a lever on the shaft in a position in which the follower is clear of the cam, and which permits the lever to oscillate when the actuating member is in its second position.

In a preferred tool according to this invention, the actuating member can be moved into a third position in which it disengages the rotary drive and substantially shuts off the air escape through the vent. In this third position the tool can be used periodically to flush out the chippings made by rock drilling, without at the same time producing more chippings.

Examples of tool according to the present invention are shown in the accompanying drawings. In these drawings:

FIGURE 1 is a sectional view of the cam follower of one tool, with most of the tool housing removed for the sake of clarity;

FIGURE 2 is a sectional view on the line II II in FIGURE 1, showing additional structure;

3,231,285 Patented Jan. 25, 1966 FIGURE 3 is a longitudinal section on the line IIII-II in FIGURE 4, showing the end of the tool including the chuck;

FIGURE 4 is a section on the line IV-IV in FIG- URE 3 showing the tool set for use as a rock drill;

FIGURE 5 is a section similar to FIGURE 4 but showing the tool set for use as a road breaker;

FIGURE 6 is a fragmentary section on the line VIVI in FIGURE 5;

FIGURE 7 is similar to FIGURE 4 but shows a different tool, set for use as a rock drill (that is to say, with the actuating member in the second position referred to in claim 1);

FIGURE 8 shows the tool of FIGURE 7 set for flushing (that is to say in the third position); and

FIGURE 9 shows the tool set for use as a road breaker (that is to say, in the first position).

The tool shown mainly in FlGURE 3 has an internal combustion engine (not shown) which is arranged to reciprocate a hammer piston 10 which delivers blows to a tool bit 11 via portion 12 (see FIGURE 3). One end 13 of the crankshaft is shown in FIGURE 2, and this end is formed as a cam comprising an ecwntric 14 around which there is a rotatable sleeve 15 which partakes of a back-and-forth movement upon rotation of the shaft. A follower in the form of a block 16 is urged against the cam by a compression spring 17 and is pivoted to an arm 18 so as to oscillate a shaft 19 to which the arm is secured. The end of the crankshaft carries a pulley starter 26.

As shown in FIGURE 4, the tool bit is of hexagonal cross-section so that it can slide in a chuck 21 but not rotate. The chuck is rotated slightly at each stroke of the hammer piston by means of a unidirectional driving connection including an arm 22 which is keyed to the shaft I} The arm 22 is forked (see FIGURE 3) so that a block 23 can be pivoted in the free end of the arm by means of a pin 24. The block is a sliding fit in a recess in a rotary member 25 which surrounds the chuck. Pawls 26 are pivoted in the rotary member 25 and are springloaded against a ratchet wheel 27 formed around the chuck, so that the pawls drive the chuck positively during anti-clockwise rotation but can ride over the teeth of the ratchet wheel during clockwise rotation of the member 25. Owing to the resistance to rotation created at the operative end of the tool bit during use, the chuck does not rotate during clockwise movement of the member 25.

Compressed air is generated in the space between a flange 28 on the hammer piston and the wall of the housing above the flange, which acts as a pump chamber and has an inlet (not shown) and an outlet, both including a non-return valve (not shown). Compressed air from the outlet is conveyed to a chamber 29 via a pipe 30 (shown diagrammatically) and a gap 31. From this chamber 29, which is at the inner end of the chuck, compressed air flows down a bore 32 in the tool bit, in the case of rock drilling.

Conversion of the tool for use as a road breaker is achieved by means of an actuating member 34. This can be moved between two extreme positions in which it engages shoulders on the housing (not shown). In each of its extreme positions the actuating member is stabilized by the engagement of a spring loaded plunger 36 in one of two notches 37.

FIGURE 4 shows the actuating member in what is termed in claim It its second position. In this position a cam surface 38 is clear of a lever 39, which is integral with the arm 22, so that the shaft 19 can oscillate. A detent 40, which is freely pivoted around the shaft 19, is urged towards the chuck by a spring 41a but is held away from the chuck by a cam surface which forms an axial 3 prolongation of the same surface 38 and which engages a finger 41 on the detent.

When the actuating member is moved to its other position (shown in FlGURE the cam surface 3% bears against hte level 39 and thus rotates the shaft 1? through an angle which carries the follower clear of the cam, as shown in dotted lines in FIGURE 2. A relieved part 42 of the cam controlling the finger 41 permits the spring 41a to urge the detent into one of a number of recesses 43 in the chuck so as to lock the chuck.

When the tool is converted for use as a road breaker by moving the actuating member to the position shown in FIGURE 5, provision must be made for allowing at least a limited escape of compressed air from the chamber 29. This is because the tool bit which is used for road breaking does not have a central passageway leading from the chamber 29, air blowing being unnecessary during road breaking. In orderto permit compressed air to escape from the chamber 2d when the actuating member is in the position shown in FIGURE 5, a passage 44 in the actuator communicates with a recess 45a in a bushing 45 surrounding the actuator, and thus communicates with the inside of the tool housing and allows compressed air in the housing to escape to the atmosphere. When the actuating member is rotated to the position shown in FIGURE 4, the end of the passage id moves out of alignment with the recess 4-5 so that the escape to atmosphere of compressed air is substantially shut off. The bushing is located in the housing by a pin 35 which extends slightly into a recess in the bushing through which air escapes when the actuating member is in the position shown in FIGURE 6.

it will be seen that the actuating member is fastened in position in the housing by means of a screw 46 and washer 47 at one end, and that the other end carries an external lever 48 by which the actuating member can be moved.

The main part of the tool shown in FIGURES 7 to 9 is the same as that of the tool shown in FIGURES 1 to 6. The tool diifers in that its actuating member 34 can be moved into an intermediate third position for flushin When the actuating member is in its second position (see FIGURE 7) a cam surface 38 is clear of a lever 39', which is integral with the arm 22, so that the shaft 1? can oscillate. A detent 46', which is freely pivoted around the shaft 19'', is urged towards the chuck by a spring 41%: but is held away from the chuck by a cam surface which forms an axial prolongation of the cam surface 33' and which engages a finger 41 on the detent.

When the actuating member is moved to its third position, which lies between the first and second positions (see FIGURE 8), the cam surface 35' bears against the lever 3% and thus rotates the shaft 19 through an angle which carries the follower lever on the shaft clear of the cam on the engine crankshaft and thus disengagesthe rotary drive. The finger 41 is still engaged by the actuating member so as to hold the detent 40' away from the chuck. In other words, when the actuating member is in its third position, air blows through the central bore in the drill bit, while rotation of the drill bit is'discontinued; this allows the operator to flush out the chippings from the hole which he is drilling, without at the same time drilling further so as to generate more chippings. This procedure may be followed from time to time whenever the operator finds that an excessive amount of drill chipping-s has accumulated in the hole.

In the first position of the actuating member (see FIGURE 9) the lever 39 is still held. in a position such that the rotary drive is disengaged, but a relieved part 42 of the cam controlling the finger 4i permits the spring ti'a to urge the detent into one of a number of recesses .43 in the chuck so as to lock the chuck and prevent rotation of the tool bit.

The vent through which compressed airis permitted to escape from the chamber 29 when the tool is used as a road breaker (see FIGURE 9) is formed by a passageway 44" through the actuating member. This passageway 44' communicates with the space 29' via recess (not shown) in the housing of the tool only when the actuating member is in its first position (see FIGURE 9). When the actuating member is rotated to one of its other positions then the passageway moves out of alignment with the recess so that the escape of compressed air to the atmosphere is substantially shut oif. The actuating member carries a lever at one end (not shown) by which it can be rotated into its three diiferent positions.

We claim:

1. A tool usable selectively as a rock drill and road breaker, comprising a chuck for receiving a tool bit, a reciprocating hammer piston, means associated with the hammer piston for striking the tool bit, a rotary drive mechanism for rotating the chuck slightly at each stroke of the hammer piston, a casing structure defining a chamber at the inner end of the chuck, means for supplying compressed air substantially continuously to said chamber at the inner end of the chuck, an air release vent defined by the casing structure and communicating with the said chamber at the inner end of the chuck, means defining a plurality of recesses spaced around the circumference of the chuck, a detent movably mounted in the casing structure, means biasing the detent towards locking engagemerit in one of the said recesses for locking the chuck against rotation, an actuating member engageable with the detent and with the rotary drive mechanism and being formed with an air-release passageway selectively communicable with the said air-release vent, and being movable selectively to a first operating position for disengaging said rotary drive mechanism, for communicating said air-release passage with said air-release vent, and for permitting said detent to move into locking engagement with one of said recesses around the chuck, and to a second position for permitting said rotary drive mechanism to rotate said chuck, for movingsaid air-release passage out of communication with said air-release vent, and for holding said detent clear of said recesses.

2. A tool according to claim 1 further comprising an internal combustion engine for driving the hammer piston, said rotary drive mechanism com rising a cam connected for rotation by said engine and a follower mounted on a shaft to be oscillated about the axis of said shaft by the rotation of said cam, a unidirectional driving connection between said shaft and said chuck for rotating said chuck uuidirectionally upon oscillation of said shaft, and means on said actuating member for moving said follower clear of said cam when said actuating member is in said first position.

3. a tool according to claim 2 in which the unidirectional driving connection comprises two co-axial rotary members, one being within the other, and one carrying one or more spring-loaded pawls which co-operate with a ratchet wheel formed on the other member, so that the pawls drive positively in one direction of rotation but can ride over the teeth of the ratchet wheel in the other direction of rotation.

4. A tool according to claim 3' in which the inner rotary member is formed around the chuck, and in which the outer member is oscillated by an arm which is carried by the shaft and of which a free end is a sliding lit in a recess in the outer member.

5. A tool according to claim 2 in which the cam is on the crankshaft of the engine.

6. A tool according to claim 5 in which the cam is in the form of an eccentric surrounded by a freely rotatable sleeve against which the follower bears.

7. A tool according to claim 1 in which the two positions of the actuating member are different angular positions about an axis of rotation, the actuating member being formed with a cam surface which controls the detent.

8. A tool according to claim 7 in which the cam surface, when the actuating member is in its second position, holds the detent away from the position in which the detent can lock the chuck, the detent being pivoted with respect to the tool housing about an aXis parallel to that of the actuating member.

9. A tool according to claim 1 in which the actuating member can be moved into a third position for disengaging the rotary drive and substantially shutting off the air escape through the vent.

it). A tool usable selectively as a rock drill and road breaker, including a chuck to receive a tool bit; an internal combustion engine having a crankshaft; a recipro cating hammer piston driven by the internal combustion engine for striking the tool bit; a rotary drive mechanism for rotating the chuck slightly at each stroke of the hammer piston, said drive mechanism including a cam on the crankshaft of the engine against which is urged a follower arm on a drive shaft transmitting an oscillatory drive to a unidirectional coupling connected to the chuck; a casing structure defining a chamber at the inner end of the chuck; means for supplying compressed air to the said chamber; a detent engageable with the chuck so as to lock the chuck against rotation, said detent being urged towards the chuck by a spring; and an actuating member movable between a first position for permitting the detent to lock the chuck against rotation, for holding the drive shaft in an angular position in which the follower arm is out of engagement with the co-operating cam on the crankshaft, and for permitting the compressed air in the chamber to escape to the atmosphere through a vent formed in the casing structure, and a second position in which the actuating member holds the detent out of engagement with the chuck, releases the drive shaft so as to permit the shaft to oscillate and hence to rotate the chuck, and substantially shuts off the air escape through the vent.

11. A tool according to claim 10 in which the actuating member can be moved into an intermediate third position for holding the drive shaft in an angular position in which the follower arm is out of engagement with the co-operating cam on the crankshaft, for holding the detent out of engagement with the chuck, and for substantially shutting off the air escape through the vent.

12. In an engine-powered percussive tool having a chuck to receive a tool bit, and a rotary drive mechanism for intermittently rotating the chuck in one direction, including a member which is driven by the engine and which performs back-and-forth movements through a predetermined path, the improvement comprising a drivetransmitting follower engageable with said member, a spring biasing the follower towards engagement with said member, and an actuating member for moving the follower out of the range of said first-mentioned member, against the action of the biasing spring, whereby the drive can be discontinued.

13. A tool according to claim '7 wherein said rotary drive mechanism comprises a rotatable cam and a follower mounted on a shaft to be oscillated about the axis of said shaft by the rotation of said cam, and wherein said actuating member has a second cam surface for moving said shaft to a position in which the follower is clear of the rotatable cam in the first position of said actuating member and to a position in which the follower is oscillated about said shaft when such actuating member is in its second position.

References Cited by the Examiner UNITED STATES PATENTS 2,764,138 9/1956 Wahlsten et a1. 173110 3,074,381 1/1963 Osgood 173-97 BROUGHTON G. DURHAM, Primary Examiner. 

12. IN AN ENGINE-POWERED PERCUSSIVE TOOL HAVING A CHUCK TO RECEIVE A TOOL BIT, AND A ROTARY DRIVE MECHANISM FOR INTERMITTENTLY ROTATING THE CHUCK IN ONE DIRECTION, INCLUDING A MEMBER WHICH IS DRIVEN BY THE ENGINE AND WHICH PERFORMS BACK-AND-FORTH MOVEMENTS THROUGH A PREDETERMINED PATH, THE IMPROVEMENT COMPRISING A DRIVETRANSMITTING FOLLOWER ENGAGEABLE WITH SAID MEMBER, A SPRING BIASAING THE FOLLOWER TOWARDS ENGAGEMENT WITH SAID MEMBER, AND AN ACTUATING MEMBER FOR MOVING THE FOLLOWER OUT OF THE RANGE OF SAID FIRST-MENTIONED MEMBER, AGAINST THE ACTION OF THE BIASING SPRING, WHEREBY THE DRIVE CAN BE DISCONTINUED. 